Monday, August 02, 2010

Ethon flew back from Boulder with long stopovers in Denver, and Lord help him O'Hare. He's been getting old and peckish, and has taken to flying commercial for long hauls. Except for the food (no liver, never), he doesn't complain much. So the Bird and Eli were sitting around discussing knowledge and the difference between Philosophy, Policy, Science and Politics, you know, Honest Broker stuff. Eli thought that it was really simple, Philosophy is thinking about what should be, and Science is thinking about what is. Policy is reconciling the two, and Politics, Politics is Jindal Berm Theology, or as Roger Jr. said to Ethon, getting elected is the only thing that counts.

Ever since he was a little kit, Eli has been hearing from the Jindal Berm School, about how 1970s science predicted a new ice age was on the way. Stoat has a cute little vanity page on the subject, and occupying pride of place, the number one "proof", the Euro-cooling Journal Article Contest Winner, has always been Rasool and Schneider, Science (1971) 138 "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate".

This, of course, is the paper which birthed the term "to be Rasooled", as denialists world wide Rasool Rasool, disappearing him down the citation hole and always refer to this as the late Stephen Schneider's paper. This is quite amusing as S. Ichtiaque has turned in to a Pielke Sr. clone, but then he never liked Jim Hansen much after hiring him. Turns out they might be right, as we shall see, yet Schneider was a young postdoc at the time, Rasool was the senior author.

So at last we come to the point of this post, how does science correct itself, and indeed it has, the consensus value of ~ 3 K/ CO2 doubling has been consistently reaffirmed many times in many ways, and the arms of the black knight, the very high (above 5K) and very low (below 2K) chopped off as improbably with numerous lines of evidence. Of course, the black knights, such as low end Lindzen keep on trying. So how are these appendixes (the vestigial useless organs) dealt with. They remain in print. Almost none are challenged in comments, but in a small community, everyone knows, word passes. However, as climate has become a policy issue with a much larger audience, this is no longer working, which accounts for the increased number of comments on seriously flawed papers and so, Eli adds a bit to the hysterical record.

As just about everyone knows, Rasool and Schneider used too low a value of the climate sensitivity to CO2 increase, although their aerosol sensitivity was not bad and that, it is important to know, was a significant contribution. A footnote, added probably at the insistence of the editor, points out that others found much larger CO2 sensitivities, which would more or less be the IPCC recommendation, 2-4.5 K for CO2 doubling.

Using their sensitivities, Rasool and Schneider tried to estimate future aerosol increases from fossil fuel burning and other sources and concluded that this

should raise the present background opacity by a factor of 4, our calculations suggest a decrease in global temperature by as much as 3.5 oC. Such a large decrease in the average temperature of Earth, sustained over a period of few years, is believed to be sufficient to trigger an ice age. However, by that time, nuclear power may have largely replaced fossil fuels as a means of energy production."

This is just about the only such prediction in the scientific literature, but has given rise to a cottage industry of claims. In the natural course of science, it was quickly and conclusively established by other calculations that R&S's value for climate sensitivity was too low, and the higher values, close to the current consensus ones were correct, and there was no danger of a new ice age. Why Eli put that in bold will soon become clear, but what it does show is the effective way that science has of correcting such mistakes. UPDATE: And as we shall see, Schneider himself soon, ok, relatively soon, corrected the error.

Still, where did that estimate for low CO2 sensitivity come from? Eli found the smoking gun in a 2000 AIP oral history interview by Spencer Weart with Jim Hanson (emphasis added)

Weart: You’ve known Schneider from way back, you said?

Hansen: Yes.

Weart: In what sense? Did you run into him at meetings?

Hansen: No, no. He was a student. He actually got his degree in engineering, but he got introduced to this topic by Ichtiaque Rasool, who was the guy who was later attacking me. The guy who got me my job and was attacking me, referring to our earlier situation. So Ichtiaque got Steve to work as a post-doc under him, I believe it was just after Steve graduated from Columbia. They wrote a paper on the effect of aerosols on climate, and ended up saying that the Earth may be headed towards the next Ice Age. I actually helped Steve with his calculations because he was not really a radiation transfer person, so I gave him equations for the scattering the solar part of the problem. He did the thermal part of the problem, and actually, he did a kind of slightly sticky CO2 calculation. He understated the greenhouse effect by a factor of two or so. We later figured out looking at his computer program that it was his mistake.

Weart: I’m curious. What was it?

Hansen: Just his calculation of the infrared opacity of the greenhouse gas greenhouse gas, CO2, was wrong.

Weart: Problem with the data?

Hansen: You’d have to ask Andy. I don’t remember the details. Andy Lacis, he’ll probably remember. What was the point? Oh, Steve Schneider. He and I went with my wife, climbing on Storm King Mountain. So we were pretty good friends.

UPDATE: Below, in the comments, Kooiti Masuda points out that

Schneider discussed in his paper in 1975 the sensitivity of climate to CO2 based on several studies available then, including Rasool and Schneider 1971.

He introduced "A useful surface temperature-CO2 concentration sensitivity parameter". Though I am not sure whether this is the very first paper to discuss it, I think we can say the paper started discussion about that parameter popular (among experts). The paper is referred to as "in press" by Broecker's 1975 "Global Warming" paper (which is discussed recently by Stefan R. in RealClimate). I think the assessment of CO2-climate sensitivity by Schneider convinced Broecker the outlook of warming.

Schneider 1975 said that Rasool and Schneider 1971 underestimated the CO2-climate sensitivity, and listed three reasons. The first included the same key word "IR (infrared) opacity" as in Hansen's talk, and I guess that both point to the same thing. The other two are more technical and I have not understood them yet. I quote the first point (p.2063).

"1) The increased CO2 increases IR cooling to space in the stratosphere (which decreases the stratospheric temperature) and increases stratospheric IR opacity. Since Rasool and Schneider maintain constant stratospheric temperature even after CO2 is doubled, their model's stratosphere emits too much infrared radiation to space. This, combined with the constraint of planetary radiation balance at the top of the atmosphere, results in a compensation process by which their model's troposphere does not warm sufficiently. This effect was modeled by Manabe and Wetherald [1967] and not by Rasool and Schneider, and, as explained by the next section [Section 3], accounts for roughly 0.5 K of the 1.6 K difference in Γ2 estimates."

11 comments:

People should be encouraged to read the entirety of both parts. It's very informative, e.g. where Hansen anticipates the discovery by A. Watts of urban warming.

Also, I notice on their list interviews with a few other prominent climate scientists, including a three-parter with Wally Broecker. There are probably some others, although it'll be a bit hit-or-miss due to the requirement for a connection to physics.

I happened to glance at the interview of Courant (by Kuhn!), which was interesting for various reasons but had this amusing/frightening passage:

"The best teacher, the most successful teacher I had at Breslau, was typical of the point of view of education, was a man in algebra, his name was Rosanes. His name is not known any more. His great success as a teacher was really due to the fact that he didn't teach things very well. He came to the platform. There was a blackboard. In his right hand he had some chalk, in the left hand he had a wet sponge. He turns his back to the audience, and he mumbled something towards the blackboard, and scribbled something in small letters on the blackboard, cover it up with his body. And as he roved along he erased what he had written. And then the student always had to try to snatch a few words. Then there was an enormous task after class, one sat there for another half hour to try to put together the pieces. If one succeeded, one really had learned enormously much. This was the basis for my learning algebra."

"The best teacher, the most successful teacher I had at Breslau, was typical of the point of view of education, was a man in algebra, his name was Rosanes. His name is not known any more. His great success as a teacher was really due to the fact that he didn't teach things very well."

I recently completed a pre-calc course. The instructor made so many mistakes that I was kept on my feet because I could not trust a thing that was said. As a result I was forced to read and reread the text, and to resort to the hair pulling labor of resolving all my dificulties on my own. Perhaps in the future I should try to find people who are not competent in their subject matter.

He introduced "A useful surface temperature-CO2 concentration sensitivity parameter". Though I am not sure whether this is the very first paper to discuss it, I think we can say the paper started discussion about that parameter popular (among experts). The paper is referred to as "in press" by Broecker's 1975 "Global Warming" paper (which is discussed recently by Stefan R. in RealClimate). I think the assessment of CO2-climate sensitivity by Schneider convinced Broecker the outlook of warming.

Schneider 1975 said that Rasool and Schneider 1971 underestimated the CO2-climate sensitivity, and listed three reasons. The first included the same key word "IR (infrared) opacity" as in Hansen's talk, and I guess that both point to the same thing. The other two are more technical and I have not understood them yet. I quote the first point (p.2063).

"1) The increased CO2 increases IR cooling to space in the stratosphere (which decreases the stratospheric temperature) and increases stratospheric IR opacity. Since Rasool and Schneider maintain constant stratospheric temperature even after CO2 is doubled, their model's stratosphere emits too much infrared radiationto space. This, combined with the constraint of planetary radiation balance at the top of the atmosphere, results in a compensation process by which their model's troposphere does not warm sufficiently. This effect was modeled by Manabe and Wetherald [1967] and not by Rasool and Schneider, and, as explained by the next section [Section 3], accounts for roughly 0.5 K of the 1.6 K difference in gamma_2 estimates."

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Eli Rabett

Eli Rabett, a not quite failed professorial techno-bunny who finally handed in the keys and retired from his wanna be research university. The students continue to be naive but great people and the administrators continue to vary day-to-day between homicidal and delusional without Eli's help. Eli notices from recent political developments that this behavior is not limited to administrators. His colleagues retain their curious inability to see the holes that they dig for themselves. Prof. Rabett is thankful that they, or at least some of them occasionally heeded his pointing out the implications of the various enthusiasms that rattle around the department and school. Ms. Rabett is thankful that Prof. Rabett occasionally heeds her pointing out that he is nuts.